This invention relates to high-speed devices and, more particularly, to all-optical devices suitable for performing functions such as switching, memory and logic in an information processing system.
It is known that self-focusing occurs when a light beam having a non-uniform spatial profile (such as a Gaussian laser beam) and sufficient intensity propagates through a non-linear medium having an intensity-dependent index of refraction. For self-focusing to be possible, the refractive index of the medium must increase with increasing light intensity
An all-optical bistable device embodying the concept of self-focusing in three dimensions is described in "Optical Bistability Based on Self-Focusing" by J.E. Bjorkholm et al, Optics Letters, Vol. 6, No. 7, July 1981, pp. 345-347. In the three-dimensional (3D) device of Bjorkholm et al, the non-linear medium consists of sodium vapor contained in a heated glass cell.
Other 3D optical devices based on self-focusing have been proposed. For example, in Optical Bistability, edited by C. M Bowden et al, Plenum Publishing Corp. New York, 1980, P. W. Smith et al describe such a device that includes an elongated waveguide (such as an optical fiber) made of a nonlinear optical material.
Self-focusing optical devices of the 3D type as heretofore described are inherently unstable and typically require a relatively large amount of optical power for operation. Such 3D devices have not therefore been generally regarded as suitable all-optical components for inclusion in a high-speed information processing system.
Recently, the observation and theory of propagating soliton (selffocused-optical) beams in a non-linear planar guides have been described ("First Observation of Higher-Order Planar Soliton Beams" by S. Maneuf et al, Proceedings of the International Commission for Optics, Quebec, Canada, 14 (1987), paper A11.2, pp. 385-386). But, heretofore, no practical two-dimensional (2D) optical devices based on such self-focusing have been reported or suggested.